1. Field of the Invention
The present invention relates to switching in a communication system, and more particularly to a system and method for processing an external handover of Digital Enhanced Cordless Telecommunication (DECT) line cards in a private switching system.
2. Background of the Related Art
In order to employ a DECT system in a private switching system, a DECT line card is installed in the switching system, and the corresponding line card is connected to a base station.
In the existing DECT system, however, only one DECT line card can be installed in the switching system. Large-capacity private switching systems having a large number of wireless subscribers thus experience problems due to this limitation. Accordingly, there have been many attempts to install at least two line cards in a private switching system.
FIG. 1 shows one such system, having a plurality of line cards 10-1 to 10-N, a Common Control Fixed Part (CCFP) 20, and a plurality of Subscriber Line Circuit (SLC) 30-1 to 30-M. Each of the plurality of line cards 10-1 to 10-N includes a plurality of Burst Mode Controller (BMC) 11-1 to 11-8N.
Each of the line cards 10-1 to 10-N can be connected to a maximum number of eight base stations, each of which can accommodate twelve subscribers. Therefore, each of the line cards 10-1 to 10-N can accommodate up to a maximum of ninety-six subscribers.
In the related art switching system having the construction as described above, the ninety-six subscribers accommodated in the same line card use the same synchronous clock. Thus, there is no problem in the handover between the ninety-six subscribers connected to the same one of the line cards 10-1 to 10-N. However, the CCFP 20 controlling all of the line cards 10-1 to 10-N in the system is required to achieve the handover between the subscribers accommodated in different line cards 10-1 to 10-N. Specifically, the CCFP 20 outputs master synchronous clocks, which all of the line cards 10-1 to 10-N use. This enables the handover between the subscribers accommodated in each of the line cards 10-1 to 10-N.
In order to perform the handover between the subscribers accommodated in each of the line cards 10-1 to 10-N, the CCFP 20 executes a signaling protocol. To execute the signaling protocol, the CCFP 20 analyzes all information for the signaling protocol for the handover between the subscribers accommodated in the all of the line cards 10-1 to 10-N, and applies orders according to the result of the analysis to each of the line cards 10-1 to 10-N. Accordingly, to achieve a seamless handover between subscribers accommodated in each of the line cards 10-1 to 10-N, the signaling signal of each of the line cards 10-1 to 10-N is supplied as protocol data between the subscribers accommodated in all of the line cards 10-1 to 10-N by means of the CCFP 20.
Further, the CCFP 20 applies an order for providing other functions, such as an Adaptive Differential Pulse Code Modulation (ADPCM) interfacing, switching, echo elimination, PCM interfacing, and the like, to each of the line cards 10-1 to 10-N. The BMCs 11-1 to 11-8N contained in each of the line cards 10-1 to 10-N carry out a series of operations for executing the protocol for the handover, according to a reception of the order.
The related art switching system has various problems. For example, it is difficult to add the related art CCFP 20 in a private switching system. Accordingly, to employ multi-line cards in such a private switching system, the system construction of the private switching system has to be redesigned to add the CCFP 20 into the system. This redesign makes the system more complicated, and increases the expense due to the addition of the CCFP.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.
An object of the invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter.
Another object of the present invention is to provide a system and method for processing external handover of DECT line cards in a private switching system that substantially obviates the problems caused by disadvantages of the related art.
Another object of the invention is to provide a system and method for processing external handover of DECT line cards in a private switching system, in which a DECT system integrated in the private switching system has a plurality of DECT line cards, which arc divided into a master line card and a plurality of slave line cards.
It is another object of this invention to perform the signaling protocol for the handover between subscribers accommodated in different DECT line cards without using a CCFP.
To achieve these and other advantages in whole or in parts, there is provided a method for processing handover of Digital Enhanced Cordless Telecommunication (DECT) line cards in a private switching system, including setting at least one as a master line card and remaining ones as slave line cards from among a plurality of DECT line cards by means of switching means; setting at least one as a master Burst Mode Controller (BMC) and remaining ones as slave BMCs from among a plurality of BMCs in the master line card, and generating a synchronous clock in the master BMC, and then applying the synchronous clock to the slave BMCs, and analyzing information about a signaling protocol in the master line card, and applying an analyzed result of the information to each of the slave line cards in accordance with the synchronous clock, so as to perform the handover between subscribers by means of a communication protocol.
To further achieve these and other advantages in whole or in parts, there is provided a system for processing handover of DECT line cards in a private switching system, including at least a master line card; a plurality of slave line cards controlled by the master line card; and a backplane for providing signal lines for protocol between the master line card and the slave line cards.
In the system and the method according to a preferred embodiment of the present invention, a plurality of DECT line cards are divided into a master line card and a plurality of slave line cards, and the signaling is performed between the line cards through an HDLC protocol. This simplifies the construction of the system, and adapts the DECT system to be integrated in the private switching system.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.